Sometimes a Securitycheck Pro configuration can result in accidentally blocking a Super User from the site. Normally that would require you to rename some folders of Securitycheck Pro' system plugin or launch some queries from phpmyadmin to unblock yourself. This can be rather complicated for some site administrators. The One Time Password feature (OTP) works around that problem in a secure manner. Visiting a special URL lets you log in to your site's administrator and unblock yourself.